1. Field of the Invention
This invention relates to a locking mechanism whereby a push rod of a baby carriage, which is turnably installed can be fixed in the face-to-back push state and also in the face-to-face push state.
2. Description of the Prior Art
FIG. 1 is a side view showing an example of a baby carriage to which this invention is applied.
The arrangement of the entire baby carriage has nothing to do with the essence of this invention, but the outline thereof will be briefly described below.
A front leg 3 having a front wheel 2 and a rear leg 5 having a rear wheel 4 are attached to a longitudinally extending handrail 1. A seat support rod 6 for supporting a seat is mounted between the front and rear legs 3 and 5. Further, the rear leg 5 has a handrail support rod 8 attached thereto through a connecting member 7. The upper end of the handrail support rod 8 is attached to the handrail 1. An upwardly extending backrest support member 9 is turnably connected at its lower end to the rear end of the handrail 1. The backrest support member 9 can be fixed at a desired angle of inclination by adjusting a backrest angle adjusting lever 11 turnably connected to a bracket 10 fixed to the rear end of the handrail 1.
A push rod 12 which has direct bearing on this invention is used to move the baby carriage, and, for example, is turnably connected to the connecting member 7 through a pin 13. The purpose of turnably connecting the push rod 12 is to obtain the face-to-face push state in which the user pushes the baby carriage while looking at the baby's face, and the face-to-back push state in which the user pushes it while looking at the baby's back. The illustrated state is the face-to-face push state. On the other hand, the state shown in FIG. 2 is the face-to-back push state. The push rod 12 has to be fixed in position respectively for the face-to-back state and the face-to-face push state. To this end, a locking mechanism 14 is provided. The locking mechanism 14 comprises a hook 15 rotatably attached to the push rod 12, and a knob 16 rotatably attached to the push rod 12 so as to make it possible to rotate said hook 15. The hook 15 has an engaging recess 19 adapted to fit on engaging pins 17 and 18. One engaging pin 17 is erected on e.g., the upper portion of the front leg 3, while the other engaging pin 18 is erected on, e.g., the bracket 10 fixed to the rear end of the handrail 1. When the engaging recess 19 of the hook 15 fits on one engaging pin 17, the face-to-face push state of the push rod 12 (FIG. 1) is fixed, while when the engaging recess 19 of the hook 15 fits on the other engaging pin 18, the face-to-back push state (FIG. 2) is fixed.
The operation of changing the face-to-face push state shown in FIG. 1 to the face-to-back push state shown in FIG. 2 will now be described. In this case, first, it is necessary to disengage the engaging recess 19 of the hook 15 from one engaging pin 17. To this end, the knob 16 is turned counterclockwise as viewed in the figure. In response thereto, the hook 15 is rotated counterclockwise, with the result that the engagement between the engaging recess 19 and the engaging pin 17 is canceled. Thereafter, the push rod 12 is turned clockwise as viewed in the figure to engage the engaging recess 19 of the hook 15 with the other engaging pin 18. In this manner, the face-to-back push state shown in FIG. 2 is fixed. A similar operation will be performed when changing the face-to-back push state shown in FIG. 2 to the face-to-face push state shown in FIG. 1. More particularly, in this case, the knob 16 is rotated counterclockwise in FIG. 2 and then the push rod 12 is turned counterclockwise. And the engaging recess 19 of the hook 15 is engaged with one engaging pin 17, whereupon the face-to-face push state shown in FIG. 1 is obtained.
As is clear from the description given above, to cancel the engagement between the engaging hook 15 and the engaging pin 17 or 18, it is necessary to rotate the knob 16 in a predetermined direction. In the illustrated example, the predetermined direction is a counterclockwise direction. However, it can happen that the operator rotates the knob 16 in a direction opposite to the predetermined direction by mistake. In a conventional locking mechanism, this erroneous operation, if repeated many times, causes damage to the locking mechanism. That is, in the conventional locking mechanism, the knob 16 is integral with the hook 15. Thus, the hook 16 and knob 15 rotate in a unit. Now, a situation resulting from rotating the knob 16 in a direction opposite to the predetermined direction by mistake will be considered. In that case, since the hook 15 is inhibited by the presence of the engaging pin 17 or 18 from rotation, an excessive force will act on the connected region between the knob 16 and the hook 15. This phenomenon, if repeated a number of times, will lead to damage to the locking mechanism.